Threshold Two Channels

Creates a binary image from an RGB image based on the pixels values in two channels. The x and y channels define a 2D plane and the two input points define a straight line. Pixels in the plane above and below the straight line are assigned two different values.

plantcv.threshold.dual_channels(rgb_img, x_channel, y_channel, points, above=True)

returns thresholded/binary image

  • Parameters:

    • rgb_img - RGB image
    • x_channel - Channel to use for the horizontal coordinate. Options: 'R', 'G', 'B', 'l', 'a', 'b', 'h', 's', 'v', 'gray', and 'index'
    • y_channel - Channel to use for the vertical coordinate. Options: 'R', 'G', 'B', 'l', 'a', 'b', 'h', 's', 'v', 'gray', and 'index'
    • points - List containing two points as tuples defining the segmenting straight line
    • above - Whether the pixels above the line are given the value of 0 or 255

  • Context:

    • Used to help differentiate plant and background
  • Example use:

Original image

Screenshot


from plantcv import plantcv as pcv

# Set global debug behavior to None (default), "print" (to file),
# or "plot" (Jupyter Notebooks or X11)

pcv.params.debug = "plot"

# Points previously defined  
pts = [(159, 128), (132, 110)]
# Create binary image from a RGB image based on two color channels and a straight
# line defined by two points
mask = pcv.threshold.dual_channels(rgb_img=img, x_channel='b', y_channel='a', points=pts, above=True)

Thresholded image

Screenshot


# Create binary image from a RGB image based on two color channels and a straight
# line defined by two points
mask = pcv.threshold.threshold_2_channels(rgb_img=img, x_channel='b', y_channel='a', points=pts, above=False)

Thresholded image (inverse)

Screenshot

Source Code: Here